Electrical connection device



Dec. 5, 1933.

J. J. BRELL 1,938,093

ELECTRICAL CONNECTION DEVICE Filed Dec. 29, 1931 Fig.1.

I INSULATION I] f I I'll NSULAT) i9 I gnowntoz cfuleos UT BreZL Patented Dec. .1933

UNITED STATES 1,938,093 v ELECTRICAL CONNECTION DEVICE Jules J. Brell, New York, N. Y., assignor of onethird to Harry Rad'zinsky, New York, N. Y.

Application December 29, 1931 Serial No. 583,668

8 Claims.

This invention relates to an improvement in electrical connection devices and to structures used in electrical work generally.

The most common form of electrical connec- 5 tion device consists of a plug-like member which receives the electric cord, the ends of the two wires contained in the cord being connected to the two blades or prongs with which the plug is provided. These blades are inserted into rem cesses in a wall receptacle or the like, where they form a contact with spring members located therein. My invention relates primarily to this type of plug although it is applicable to many other devices of generally similar form.

One objection found in these plugs is that the user generally disengages them from their connection with a wall receptacle by pulling vigorously on the wire cord which exerts strain upon the ends of the wires in the cord, causing them to break or become loose from their positions beneath the fastening screws for the contacts.

An object therefore of my invention is to provide a means for securely holding or anchoring the cord within the plug and relieving the strain on the wire ends, so that when the cord is pulled to withdraw the plug from its engagement with the wall receptacle, the pulling strain imposed on the electric cord is removed from the ends of the same. I

My improved fastening means is of such construction that it securely anchors the cord in the plug without in any way injuring the insulation of the cord or possibly causing a short circuit. I am aware that efiorts have beenmade in the past to anchor an electric cord or wire securely within an electrical connection plug. One of the difficulties with the devices that have been heretofore proposed is that such prior structures did not serve to securely grip or hold in position electric cords or wires of different size orcross sectional dimension. The result is that such devices could not be put in universal use. My improved cord-retaining means is of such'construction that it will operate upon almost any crosssectional size of cord or wire. Its use, therefore, is a very flexible one and accordingly only. one size of plug structure is adaptable for use with any size of wiring cord.

An additional difliculty with connection plugs in use to-day, is the tendency of the plug to be easily dislodged or inadvertently pulled out of the receptacle into which it is fitted. The connection tongues or blades on electrical connection plugs do not form a positive or gripping. engagement 55 with the spring contacts found in the various types of receptacles that are used so that an easy separation of the plug from its receptacle occurs. After a relatively short time the springs in the electrical receptacles weaken and do not exert sufiicient pressure on the tongues or blades on the plug so that the plug is easily accidentally separated from its connection with the receptacle. This is particularly true in the case of vacuum cleaners and other household electrical appliances where a lengthy electric cord or wire is used. In such instances the weight of the cord very easily pulls the plug from its socket or receptacle.

An object therefore of this invention is to provide a means for positively connecting an electrical connection plug or the like to' its receptacle whereby the plug will be held firmly and securely connected until manually removed. I

'am aware that efiorts have been made to attach electrical connection plugs to their receptacles with a snap connection, such connection being generally provided between the electrical contacts on the plug and receptacle. Structures of that kind constitute a departure from the standard universally-used type of plug and were found impracticah- Some of them were complex in structure and occupied so much of the internal space provided in the connection plug that the plug did not possess the required strength,

sturdiness andv insulating characteristics required in the standard type of plug.

My improved plug is one wherein the conventional contact blades and other parts of the standard plug structure are retained. The

'means provided for establishing a positive or snap connection between the plug and its receptacle is wholly independent of the electrical contacts on the plug and on the receptacle. Additionally, the plug forming the subject matter of this invention is one which can be interchangeably used with any of the types of well-known or standard electrical receptacles in use to-day. When used in connection with a type of electrical receptacle also forming, the subject matter of this invention, the plug forms a positive or snap connection with the receptacle and cannot be inadvertently separated therefrom.

The objects of my invention are, therefore, to provide an electrical connection device in which the electric cord is securely anchored in position, and to provide a means for securely and positively holding the electrical connection device or plug in positive engagement with a receptacle or the like.

In hereafter describing my invention as being applied to the conventional type of two-bladed connection plug and receptacle therefor, I wish to be understood as meaning that this invention may similarly be applied to various articles, de-

vices and appliances wherein a means for anchoring anelectric cable or cord is required, or where two parts of an electrical device are adapted to be brought together to close a circuit and where a means is needed for joining said parts together with a positive or snap connection. Since there are a multitude of articles and devices wherein such an arrangement is not only desirable, but necessary, space does not permit'a description of them all.

In the accompanying drawing Fig.. 1 is a side 1 elevation of an electrical connection plug showing one embodiment of my invention; Fig. 2 is a sectional view on the line 22 of Fig. 1, looking in the direction of the arrows; Fig. 3 is a plan view of the plug; Fig. 4 is a sectional view through the plug taken at right angles to that of Fig. 2, the plug being shown connected to a receptacle of the character known as a supplemental or convenience outlet; and Fig. 5 is a sectional view through a modified structure showing one of the features of my invention applied to an outlet box or the like.

In the embodiment of my invention shown in Figs. 1 to 4 inclusive, 1 indicates the shell of an electrical connection plug. This is preferably made of any of the well-known kinds of insulating material commonly used, such as hard-rubber, Bakelite, or the like. The plug has two spaced blades or contact prongs, each of which is provided with a screw 3 under which the ends 4 of the two wires 14 and 15 are secured. These elements are all found in the standard type of connection plug in use to-day. Located between the two blades 2 is a propjection 5 which is formed or moulded as a part of the plug shell, and which is provided with a recess 9 in its upper end in which is seated a snap-fastener member 7 provided with a ring or spring element 6. The snap fastener member 7 is secured within the recess 9 by means of a rivet 10, or in any other desired way. It is preferable to locate said snap fastener member in a depressed position within the recess 9 so that there is no possibility of the same bridging the two blades 2 to cause a short circuit between them. The projection 5 is provided with a central longitudinal bore 11 from which a pair of diagonally disposed openings 12 and 13 extend. The electric cord 16 made up of the two wires 14 and 15 extends upwardly through the borell and the two wires 14 and 15 diverge and project through the openings 12 and 13 to the ends of the blades 2 'where they are attached at 4 by the screws 3. a v

The shell 1 of the plug is provided with an externally threaded portion 17 on which a' lock nut 18 is adjustably mounted. At 19 is shown a cord or similar flexible member which has its two ends fixed or anchored at 20 and 21 in the body of the shell 1. This cord extends through openings 24 in a cap 22 and is provided with a loop portion 19a which extends over the end or top of the cap 22. and passes to one side of the central raised projection 33 provided thereon as clearly shown in Figs. 1 and 3. The cap 22 is internally threaded as at 23 and is normally received upon the threaded portion 1'7 of the plug 1. The electric cord 16 passes through a bore 25 provided in the cap 22. The means for securely holding the wire or cord 16 in position in the plug, and preventing it from being pulled loose therefrom, will now be readily understood. The same consists ofthe cord 19, which, when the cap 22 is threaded upon the part 17 of the plug 1, wraps itself tightly about the cord 16 in a series of convolutions as shown in dotted lines in Fig. 2, and in full lines in Fig. 4. The cap 22 when threaded upon thepart 17 is rotated until the cord is wound or Wrapped very tightly about the electric cord 16 and the lock nut 18 is then broughtup against the cap 22 to. lock it in position. This securely anchors the electric cord 16 in place and prevents the same from being pulled loose from the plug under all conditions of use. In Fig. 4 is shown the means for holding the plug in engagement with a receptacle or the like. The receptacle shown for illustrative purposes at 27 is a type commonly known as a convenience outlet. Since its structure is generally well known, full details of it are deemed unnecessary. Suffice it to say, that the same generally con-' sists of a cup-shaped shell of insulating material containing a pair of spring contacts 28 to which the ends of a wire cable 31 are attached. The plug 1 has its prongs or blades 2 inserted into the receptacle 27' and these prongs or blades are brought into contact with the spring members 28 as is sho in dotted lines. At 29 is shown the fastening screw which extends through the outlet 27 and which secures it to a wall 26 or other like support. A head 30 is formed on the fastening screw, said head being so shaped that it constitutes a snap-fastener male member adapted to snap into engagement with the fastener spring element 6 with which the plug 1 is provided. Thus, when the plug 1 hasits contact blades 2 inserted in the receptacle 2'7, its snap fastener element 7' engages with the head 30 of the fastening screw 29, with the result that the plug 1 is held securely connected to the receptacle until manually disconnected. The snap engage- 5 ment between the receptacle 2'7 and the plug 1 is secured entirely independent of any of the electrical contacts possessed by the plug or the receptacle. The plug 1 may thus be used in any type of electrical receptacle although, of course, it will not actually form a snap engagement. therewith unless the receptacle used is provided with a co-operating snap fastener member. The receptacle 27 need not be of the particular structure disclosed but may be a wall re- 5 ceptacle, a screw-threaded plug, or may be in any of themany forms with which an electrical connection plug, such as shown at 1, is adapted to engage. The plug l also need not be in the particular form disclosed. For instance, it might be the base of a radio tube having a snap fastener member 7 located between the tube prongs and sunk in the base and adapted to engage with a complementary snap fastening member located on the tube socket. The member 1 also might assume the shape or contour of the type of plug used on electric irons and similar household electrical appliances. It may assume also many of the other shapes of plugs and connection members in common use -to-day, withoutdeparting from the spirit of this invention. In Fig.- 5 is shown a modification of the means for anchoring the electric cord inposition. There a part of a wall, partition or part of an outlet box is indicated at- 35. Such part 35 might also be the rear of a radio cabinet or other electrical appliance, from which a wiring cord 38 is adapted to protrude. A bushing 36 is fitted through an opening in the wall 35, and is provided with an externally threaded portion 39 on which a lock nut is adjustably mounted. A cord or similar ed to the tubular member and its other end conflexible member is provided with the two parallel portions 41 and 42 similar in structure to the cord shown in Fig. 2. The cord 41 extends through a cap 43 which is intemally threaded at and is adapted to be received upon the threaded part 39 of the bushing 36. The electric cord or wire 38 extends through the core 37 of the bushing 36 and also through the bore 44 provided in the cap 43. To firmly hold the wire 38 against longitudinal displacement, the cap 43 is threaded upon the part 39 until the cord elements 41 and 42 are tightly wrapped about the wire 38, whereupon the lock nut 40 is drawn up against the end of the bushing 43 to prevent it from unthreading. With this constructionthe wire 38 is flrmly anchored in position ,andcannot be shifted longitudinally under any reasonable strain or pull.

In describing the elements shown at 19 and 41 as a cord I wish that term to be understood as meaning any sinuous, flexible conformable member, such as a cord, string, tape, lace or the like, capable of being tightly wrapped about the electric wire regardless of diameter of Y the wire and which will by reason of its flexibility closely conform to the wire and grip it securely. I-am aware that efforts have been made to secure an electric cord in a plug by contracting'the coils of a spiral spring about the electric cord. Thishas been found unsatisfactory because of the fact that electric cords are of varying cross-sectional shapes so that the contracted coils of the spring fail to closely conform to the shape of the electric cord. In some instances, when springs were tightened about the cord, their coils cut through the insulation and caused short-circuits in the wiring. All of these deficiencies are remedied by the structure of this invention, as the flexible, sinuous cord employed, wraps tightly about the electric wire regardless of its diameter and crosssectional shape. Moreover, even if the cord should be so tightly wrapped about the wire that it should cut through the insulation thereon, the

cord being a non-conductor, would not be likely to cause a short-circuit.

These and.various other modifications of my invention may be made without the spirit of the same.

What I claim is:-

1. A device of the class described comprising a 'plug member having a bore through which an electric wire extends, a threaded portion on said plug at the rear of the same, a cap rotatable on said threaded portion, a'rlexible cord extending between and having its opposite ends connected to the plug member and the cap and adapted to be tightly wrapped about the electric wire by movement of the cap on the threaded portion of the plug member. I

2. A device of the class described comprising a tubular member having a central opening for the reception of an electric wire, a threaded portion on said member adjacent one end of the same,

. a cap rotatable on said threaded portion, a flexible sinuous cord having one 01' its ends connectdeparting from; v I flexible cord having one of its ends attached to nected to the cap'and adapted to be wrapped about the electric wire by rotative movement of the cap on the threaded portion of the tubular member.

3. A device of the class described comprising a plug member having an opening for the reception of an electric wire, a threaded portion at the back of the plug member, a cap adapted to be rotated on said threaded portion, said cap having an opening through which the electric wire passes, a flexible sinuous cord having one of its ends secured to the plug member and its other end connected to the cap and adapted to be wrapped about the electric wire by movement of her, and means on the plug member for locking the cap in a position of adjustment.

4. A device of the class described comprising a plug member adapted to receive an electric wire, a flexible cord having one of its ends connected to the plug member, a cordtightening memher adapted to be received on the plug, the opposite end of the cord beingconnected to'said tightening member so that when said cord-tightening member is rotated relative to the plug the cord is tightly wrapped about the electric wire.

5. A device of the class described comprising a plug element adapted to receive an electric wire, a flexible, sinuous cord having one of its ends connected to the plug, and a cap adapted to be received on the plug, the opposite end of the cord being attached to said cap'so that the cord is tightly wrapped about the wire regardless of the cross-sectional shape of the wire, by rotative movement of the cap relative to the plug.

6. A device of the class described comprising a plug element through which an electric wire ex-' tends, a flexible ,Icord-like wrapping element atta'ched to the plug element, a cord-tightening member through which the wrapping element extends, said cord-tightening member being movable on the plug with a rotative movement to wrap the cord-like wrapping element tightly about the electric wire.

7. A device of the class described comprising an element adapted to receive an electric wire, a

said element and adapted to be tightly wrapped about the wire, a cord-tightening member attached to the other end of the cord and adapted to be rotated relatively to the element which receives the wire to wrap' the cord about the wire, and means on the element for rotatably receiving the cord-tightening member.

8. A device of-the class described comprising a plug element into which an electric wire extends, a flexible cord having one end attached to the plugelement, an adjustable member rotatable on the plug, the opposlteend of the cord being attached to said member, and means for locking the adjustable member in position on the plug element. a

- JULES J. BRELL. 

